IRRIGATION REGULATION

TECHNOLOGY

DAVID ZALUBOWSKI/ASSOCIATED PRESS The USDA analyzes images captured by drones, including the one held by intern Alex Olsen, to monitor the irrigation levels required for crops planted along the Colorado River.

Farmers, researchers use drones to help save endangered Colorado River

By Dan Elliott

ADRONE SOARED OVER a blazing hot cornfield in northeastern Colorado last July, snapping images with an infrared camera to help researchers decide how much water they would give the crops the next day.

After a brief, snaking flight above the field, the drone landed and the researchers removed a handful of memory cards. Back at their computers, they analyzed the images for signs the corn was stressed from a lack of water.

This U.S. Department of Agriculture (USDA) station outside Greeley, Colo., and other sites across the Southwest are experimenting with drones, specialized cameras and other technology to squeeze the most out of every drop of water in the Colorado River — a vital but beleaguered waterway that serves an estimated 40 million people.

Remote sensors measure soil moisture and relay the readings by Wi-Fi. Cellphone apps collect data from agricultural weather stations and calculate how much water different crops are consuming. Researchers deliberately cut back on water for some crops, trying to get the best harvest with the least amount of moisture — a practice called deficit irrigation.

TECHNOLOGY

USDA researchers Kevin Yemoto, left, and Huihui Zhang use cameras, sensors and other technology to chart crop growth and conserve water. DAVID ZALUBOWSKI/ASSOCIATED PRESS

In the future, tiny needles attached to plants could directly measure how much water they contain and signal irrigation systems to automatically switch on or off. “It’s like almost every month somebody’s coming up with something here and there,” said Don Ackley, water management supervisor for the Coachella Valley Water District in Southern California. “You almost can’t keep up with it.”

Researchers and farmers are running similar experiments in arid regions around the world. The need is especially pressing in seven U.S. states that rely on the Colorado River: Arizona, California, Colorado, Nevada, New Mexico, Utah and Wyoming.

The river had plenty of water last summer after an unusually snowy winter in the mountains of the West. But climatologists warn the river’s long-term outlook is uncertain at best and dire at worst, and competition for water will only intensify as the population grows and the climate changes.

The World Resources Institute said the seven Colorado River states have some of the highest levels of water stress in the nation, based on the percentage of available supplies they use in a year. New Mexico was the only state experiencing extremely high water stress.

The river supplies more than 7,000 square miles of farmland and supports a $5 billion-a-year agricultural industry, including a significant share of the nation’s winter vegetables, according to the U.S. Bureau of Reclamation, which manages many of the big dams and experimenting with reduced water for

reservoirs in the Western states. the midsummer crop, which requires

The Pacific Institute, an environmore irrigation but produces lower

mental group, says the river also yields.

irrigates about 700 square miles in Sensors placed over the test

Mexico. plots indirectly measure how

Agriculture accounts for much water the plants are

approximately 80 percent using, and the harvested crop

of water consumption in the U.S., according to the USDA. The problem

AGRICULTURE ACCOUNTS FOR

is weighed to determine the yield.

“The question then

facing policymakers is how to divert some of that water to meet the needs of growing cities without drying up

80%

becomes, what’s the

economic value of the lost crop versus the

economic value of the saved water?” said

farms, ranches and the environment.

PRECISION IS KEY

The researchers’ goal is understanding crops, soil

OF WATER CONSUMPTION IN THE U.S.

SOURCE: USDA Bart Fisher, a thirdgeneration farmer and a member of the irrigation district board. Blaine Carian, who grows grapes, lemons and

and weather so completely that farmers know exactly when and how much to irrigate.

“We call it precision agriculture, precision irrigation,” said Huihui Zhang, a USDA engineer who conducts experiments at the Greeley research farm. “Right amount at the right time at the right location.”

The Palo Verde Irrigation District in Southern California is trying deficit irrigation on alfalfa, the most widely grown crop in the Colorado River Basin. Alfalfa, which is harvested as hay to feed horses and cattle, can be cut and baled several times a year in some climates. The Palo Verde district is dates in Coachella, Calif., already uses deficit irrigation. He said withholding water at key times improves the flavor of his grapes by speeding up the production of sugar.

He also uses on-farm weather stations and soil moisture monitors, keeping track of the data on his cellphone. His drip and microspray irrigation systems deliver water directly to the base of a plant or its roots instead of saturating an entire field.

SAVING WATER AND MONEY

For Carian and many other farmers, the appeal of technology is as much about economics as saving water.

“The conservation’s just a byproduct. We’re getting better crops, and we are, in general, saving money,” he said.

But researchers say water-saving technology could determine whether some farms can stay in business at all, especially in Arizona, which faces cuts in its portion of Colorado River water under a drought contingency plan the seven states hammered out last year.

Drone-mounted cameras and yield monitors — which measure the density of crops like corn and wheat as they pass through harvesting equipment — can show a farmer land that is productive and soil that is not, said Ed Martin, a professor and extension specialist at the University of Arizona.

“If we’re going to take stuff out of production because we don’t have enough water, I think these technologies could help identify which (crops) you should be taking out,” Martin said.

Each technology has benefits and limits, said Kendall DeJonge, another agriculture department engineer who does research at the Greeley farm.

Soil moisture monitors measure a single point, but a farm has a range of conditions and soil types. Infrared images can spot thirsty crops, but only after they need water. Agricultural weather stations provide a wealth of data on the recent past, but they can’t predict the future.

“All of these things are tools in the toolbox,” DeJonge said. “None of them are a silver bullet.”